Method of making cyanids.



UNITED STATES PATENT OFFICE.

JACOB GROSSMANN, OF MANCHESTER, ENGLAND.

METHOD OF MAKING CYANIDS.

SPECIFICATION forming part of Letters Patent No. 671,479, dated April 9,1901.

Application filed June 20, 1900. Serial No. 21,007. (No specimens.)

To all whom it may concern:

Be it known that I, JACOB GROSSMANN, a subject of the Queen of GreatBritain, residing at Manchester, in the county of Lancaster, England,have invented a new and useful Improvement in the Manufacture of AlkaliOyanids and Ferrocyanids, of which the following is a specification.

My invention relates to the manufacture of alkali cyanids andferrocyanids. Researches made by Fleck in 1863 showed that sulfocyanidis formed when sulfate of ammonia is added to a fused mixture of liverof sulfur and carbon. This reaction takes place with great violence, andit was found not to be practicable on a large scale. If, however,instead of using sulfate of ammonia am moniagas be passed over a red-hotmixture of potassium sulfid and carbon or of liver of sulfur and carbon,the reaction takes place in quitea different manner. The principalprodnot then formed is potassium cyanid, sulfocyanid being only formedin quite negligible quantities. The greater part of the sulfur passesaway as sulfureted hydrogen or ammonium sulfid, respectively. Ammoniumcyanid can hardly be shown to exist in the gases which are evolved, noteven if instead of ammonia a mixture of ammonia and carbon monoxid beused.

In order to work this process on a large scale, one may proceed asfollows: The sulfid of an alkali or its liver of sulfur or ingredientsforming an alkaline sulfid at a red heat are mixed with ground or raspedcharcoal or other carbonaceous matter. This mixture is placed in retortswhich are arranged in such a manner that several retorts are connectedtogether into one set or system, so that the gas or gases which are usedin the processthat is to say, ammonia by itself or mixed with othergases-pass from one retort into another and so on into each retort ofthe set, the temperature in all retorts being kept at red heat. A heatof between 700 centigrade to 800 centigrade is sufficient. Thus when thecontents of the retorts have attained red heat the ammonia-gas in excessis passed from an ammonia-still or from a gasometer over the mixturewhich is contained in the first retort. The excess of the ammonia mixedwith other gases which are evolved in the first retort during theprocess pass into the second retort, &c. The gases which leave the lastretort of the set are condensed in the usual manner and reconverted intoammonia-gas according to methods Well known. The ammonia used in theprocess is dried by dephlegmation. It is not necessary to use chemicalagents for drying the same. After a sample taken from the first retortshows that the reaction has proceeded sufficiently, as far as theformation of cyanid is concerned, the first retort is disconnected fromthe system and emptied. Air is excluded during the emptying process, orthe retorts may be emptied in an atmosphere of a non-oxidizing gas. Thesecond retort now becomes the first in thesystem, while the first retortafter being charged becomes the last retort of the set and is exposed tothe action of the gases last; but it is not coupled into the systemagain until its contents have reached a temperature of about 700centigrade.

As regards the charge for the retorts, the qauntities are chosen in sucha way that the mass does not cake at red heat. If sulfid is used, aboutequal parts of sulfid and charcoal may be taken. If working with liverof sulfur, a good proportion will be to take on every one hundred partsof potassium carbonate about one hundred and twenty to one hundred andforty parts of charcoal and twenty-four parts of sulfur. In either casethe quantity of charcoal may be reduced. If sodium compounds are used,the proportions may be altered accordingly. Mixtures of potassium andsodium compounds may also be used in this process.

The ammonia may be prepared by any of the known methods. Compressedammonia may also be used. The ammonia-gas need not be pure. It maycontain other volatile ammonia compounds or may be mixed with carbonmonoxid, hydrogen, hydrocarbons, or other gases of a non-oxidizingnature, and it may be passed through the retorts at ordinary,diminished, or augmented pressure as compared with the pressure of theatmosphere.

If it is intended to manufacture ferrocyanids, iron-filings or suitableiron compounds may either at the beginning or at the end of the reactionbe added to and mixed with the mass contained in the retorts. It is,however,

advantageous, even in working for the production of ferrocyanidcompounds, to effect the conversion into ferrocyanid outside the retortsfrom the alkali cyanid which is in the resulting mass. It is thereforemore advantageous to lixiviate this massi. e. the drawncharge-systematically after it has been cooled in suitable apparatus.From the liquor thus obtained alkali cyanid may either be separated assuch or, after treatment With suitable ferrous compounds, asferrocyanid. The mother liquor may be evaporated in vacuum-pans or inother suitable manner and the residue returned into the process.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatWhat I claim is p 1. The herein described process for the manufacture ofalkali cyanids consisting in passing ammonia-gas over a mixture ofcarbonaceous matter and a sulfid of an alkali at a temperature of from700 to 800 centigrade, essentially as described.

2. .The herein described process for the manufacture of ferrocyanidsconsisting in passing ammonia-gas over a mixture of carbonaceous matterand a sulfid of an alkali at a temperature of from 700 to 800 centigradeand adding to the products of reaction suitable iron compounds for thepurpose of converting the cyanids first formed into ferrocyanids,substantially as described.

In witness whereof I have hereunto set my hand in presence of twowitnesses.

JACOB GROSSMANN.

Witnesses:

WILLIAM EDGAR SIMS, GEORGE HENRY RATCLIFFE.

